Process for separating hydrocarbon waxes



July 15, 1952 A. A. SCHAERER PROCESS FOR SEPARATING HYDROCARBON WAXE IS Filed March 31, 1950 VAPOR TEMPERATURE AT A M. PRESSURE,

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% DIS'HLLATE- FIGLYI July 15, 1952 A. A. SCHAERER PROCESS FOR SEPARATING HYDROCARBON WAXES Filed March 31, .1950

5 Sheets-Sheet 5 |NVENTOR= AUGU$T A. $CHAERLR t H\$ AGENT "paralfinwaxes having Patented July 15, 1952 PROCES S FOR'SEPARATING IIYDROCARBON WAXES s August A. Schaerer, Berkeley, Calif., assignor to Shell Development Y Calif., 1a cor-poraiion Company, San Francisco,

f Delaware 1 l ApplicationMarchiv l, 1950,'Serial No. 153,210

'Thismvention relates to the art ofseparating hydrocarbon waxes. .More particularly it pertains to the separation and-recovery of various types of hydrocarbon waxes from r'nixtures thereof. Still more specifically,it pertains to the-separation from waxy miner 'loil stocks, including such stocks'as contain a r-predom inant proportion of paraffin wax such as of the characterofslack andthe like, of normal or straight-chain parafimwaxesf contained therein, separately from non-straight chain or isomeric (isoand cycles) paraifinwaxes also contained therein. v "Various methods have been used andsuggested for therecovery and/ or fractionation of paraffin 'waxesfrom'mineral oil stocks. Thus, it is known to'dewax waxy mineral oils or fractions thereof bycooling, sometimes after addition of -a sol-vent and 7 1%- diluent. Dependent-onthe mature of 'tlie 'onand {the conditions-of the operation, such as lowest cooling temperature, rate-of coolinggmanner'of cooling, "etc the "paraffin wax th-us obtained" has been either in the form" of readily filterable crystals or of I a poorly filterable, microcrizstaJ-llineor amorphous product. The crystal- --line,readily filterable, products are =usually1obtained in connection with dewaxing operations .as ep neerw paraffinic lubricating oil distillate-stock and -c'onsist largely of high molecular weight aliphatic or paraifinic "hydrocarbons with a straight chain, -i. "e. 'n-par-amns, whereas the '-micro'crystalline or amorphous products consist, at -least toa large and controlling extent of h'igh molecular weight aliphatic hydrocarbons of a branched character includingbranched-chain and -ring-con'taining hydrocarbons, generally termed i'soparaffins and cycloparaffins respectively, both classes of which may be termed as '18 Claims. (Cl. 196-17) isomericparaflins trelative to the 'n-para'fiins).

"Frequently occurring--'cycloparaffins in mineral oils are paraffins having a naphtheni'c ring, gen} orally 'oi f'lve or six carbon atoms per ring to which is bound a straight. or :branched aliphatic hydrocarbon chain. 'dewax'ing operations, with or without the *aid of slvents-arid/or :diluents, generally contain .ap- *preciableproportions of oil. These waxes .are usually de-oiled 'by a so-called sweating and filtering process and/or a solvent deoilin'g process; r 1 l =The zip'araffin hydrocarbon waxes on the one hand and the 'non-straig'ht-chain paraffin'hydrocarbon waxes on theotherhand have properties which -in manyrespects are widely divergent.

I-hesedifferences in properties account, for example; for 'the differences i-n-applications or -uti-lityof ithe -paraflin waxes and the isomeric paraffin waxes. Thus, for instance," normal atleast '22 carbon atoms per molecule are particularly :suitable for the manufacture of candles (candle wax) and parafiin papenwhile lthe isomer-ic-(isoand cyclo-) paraffin waxes, especially those having more than Waxes obtainedloytheusual 2 I approximately 26 carbon atoms per molecule, in an oil-free state, farm useful products on account of their-plastic properties and'adhesion to glassiand tometal articles I In View of the differences in properties between straight'chain or normalparafiin waxes on the one .hand, and :the isomeric paraffin waxes on the other hand, it is desirable and, therefore, an object .of this invention to provide an improved process whereby they may be obtained from waxy petroleum stocks andseparatelyfrom each other. 'A :further object is to :provide an improvedrprocess for the separationnf'nrparaffin waxes from isoand/or cyclorparafiin "waxes and/or from'oils in admixture-therewith, and at the same :timefto separate the n-Vparaflin waxes into various fractions thereof approximating those of single molecular species. Another'object of .the invention is :to :provide an improvedprocess for idewaxing waxy :.oils and separating and ,recovering the waxes as desirable fractions of n- .:paraffinic waxes and of isomeric paraffinicwaxes. Still another object is to provide an improved process for .de-oiling oily waxes and separating and recovering the waxes as desirable fractions of n-parafiinic hydrocarbon waxes .and .;of 1S0? and/or cyclo-paraffinic hydrocarbon waxes'..

The foregoing objectswill be'b'etteriunderstood and others will become apparent from "the following description of the invention, be made with reference to the accompanying drawings,-wherein: v a V Fig. I is a graphicalrepresentation of the relationships between the boiling points, :themelting points and the number of carbon atoms per molecule of ,parafiin hydrocarbons containing from 20 to 35 carbon atoms per molecule;

Fig. 11 shows graphically the solubility-temperature relationships of various normal paraffin wax hydrocarbons in methyl isobutylketone;

Fig. III shows graphically the solubility-temperature relationships of a high melting crystal- Tlinewax and of an amorphous paraffin wax various organic solvents;

Figs. .IV and V are graphs showing the influence of fractional distillation on the separation :by crystallization of the waxes in waxy petroleum distillates;

Fig. VI shows graphically the distillation characteristics of the various distillate fractions represented in Figs. Iliand V; and

Fig. VII is a diagrammatic .fiow .sheet of a process for the fractionation .of paraflin waxes in accordance 'with an embodiment .of the invention.

It has now been found that 'normal' '(i. .e., I

which will 7 melting point, oily,

of which has a relatively small range'of carbon atoms per molecule (3 to 4), and contains both straight-chain parafiins and non-straight-chain parafims within that carbon-atom-per-moleculef range, and fractionating at least that fraction,

number of carbon atoms per molecule, then the .normal paraffin waxes present in each such fraction may be readily separated as substanof wax composed substantially entirely of at least a substantial portion up to substantially all of the straight-chain paraffin hydrocarbons present in the narrow-carbon-atom-range fraction, and

a second, lower melting point, fraction composed essentially of -the non-straight-chain paralfin hydrocarbons. It is also contemplated to adjust the temperature of the second fraction, preferably'inthe presence of a solvent or diluent, to a point'such thathigher melting point nonstraight-c'hain paraflin hydrocarbons present therein are precipitated from lower. melting point, oily, non-straight-chain paraffins present. In accordancewith a preferred embodiment of the invention, the waxy mixture is fractionated into a plurality of fractions-having small carbonatom-per-molecule ranges, respectively, and each fractionisth'en fractionated according to'melting points of parafiinlwaxes present in the respective fractions, to produce from' each fraction a first, higher melting point, fraction, com posedsubstantially entirely of at least a substantial portion up to substantially all of the straight-chain paraiiinv hydrocarbons present in the particular fraction lthusffractionated. Still further, the remaining portionv of each fraction so fractionated may be fractionated separately at a still lower temperature to precipitate the higher-melting point ncn-straight-chain paraffin hydrocarbons present "therein from the lower non-straight-chain paraffins present, or any two onmore-of the remaining portions may be combined .intoone or more con carbonandthen'fractionated at a suitable temperature to separate isoand .cyclo parafiinic hydrocarbons having melting points above a selected melting. point from oilyfhydrocarbons having melting points below that melting. point.

The invention is applicable to the; separation of normal parafiinwaxes from is'oandcycloparafiin waxes from mixtures composed for the mostpart of such Waxes. -.It,.is equally applicable to the separation of such waxes when they separation and recovery of the isoand cycloparaffin waxes, from highly paraffinic and paraffinic-naphthenic petroleum lubricating oil base stocks and distillates therefrom.

The present invention is based on the discovery that when a parafiinic petroleum waxy mixture of hydrocarbons is vfractionated into narrow molecular weight range fractions, that is;'.into,

fractions which the range of carbon atoms permolecule issmall, such as '3 to 4, and preferably 2 or 3, which fractionation may be effected bymaking relatively sharp and narrow boiling 'posite fractions cfnon-straight-Chain hydrorange distillate, fractions therefrom, since thew boiling points of; the normally solid; parafi'inic waxesgare substantially the same for both normal and isomeric parainnic waxes having the same of mercury pressure.

substantially. all of" the tially'purenormal :paraifin waxes from the re- .mainder of the fraction. by fractional crystallizationof said frac'tion in a fluid state, either umoltenor dissolved'in an organic solvent, since the melting points of the'paramnic waxes depend both on the molecular weight and on the "molecular structure and the melting point of the non-straight-chain hydrocarbons by fractional precipitation at a su without added diluent or solvent.

The fractionation of the waxy mixture ac.- cording tomolecular size or weight is most advantageously and preferably efiected by an efiicient fractional distillation, preferably underreduced pressure,at least for thehigher molecular Weight hydrocarbons, hich distillation is carried out in sucha manner as to'eifect a relatively sharp separation between thehydrocarbons'ha'ving difierent r boiling temperatures. The fractionation of:hydrocarbons by distillation according-to molecular weights and carbonatom-permolecule-content willbe. understood more readily by reference to the graphical 'representationsof the relationships-between the boiling points and the carbonatoms per molecule. of various types of paraffin hydrocarbons, as shown in Fig. I. The upper curve (normal parainns)v in Fig. I was constructed from-the boiling points of the normal paraffin hydrocarbons having from 19 to. 36 carbon atoms per molecule. The next solid curve thereunder represents, the. boiling point-carbon atom per molecule relationship for all parafiinic hydrocarbons, the melting points being averaged for all paraffins having a given carbon-atom-per- .molecule content. The boilin points represented at 15 mm. The numerical values for the boiling points of the paraffins and for the melting points of the-straight-chain paraffins, from which the curves were constructed, were on both these boiling point curves are taken fromPhysical Constants of the Principal Hydrocarbons, by M. P. Doss, 4th Edition, 1943, and Physical Constants of Hydrocarbons,-by G. Egloif, A. C. S. .MonographSeries No. 78, vol. II, 1940. Conversions of boiling points from reported values to 15 mm. of Hg pressure, where the reported valuewas for a different pressure,

were made by utilizing the conversion chart given by Watson and Wirth, in Ind. and Egn. Chem, Anal. Ed., vol. 7, page 73, January 1935.

The upper dashedline-in Fig. -I is a straight line with a slope of about 853C. (at 15 mm. Hg) ,-:per unit carbon--atom-per-molecule change and, as-is-readilyseen, represents within about 2 C. the boilingpointszof the normal parafiins from C20 to C35, andalso-represents Withinfrom about 2 C. to about.5 C. the. bo lin points of parafiinic :hydrocarbons from Cm to C36. As indicated in Fig. I, this re lationship is expressedby the equation: 7

: Boi in point I foriintegral values or n from about 20 to about a.

able temperature, with or chain} and non-straight -chain the practice of -the-invention, it'has been found and wherein n is the number of carbon atoms per molecule of the parafiinic hydrocarbon. EAccording to the dashed line and the equationgthre is-a change in boiling points, of paraffinic -hydrocarbons having from about-20 to about 36 carbon atoms per' molecule, 'at 15 .mm. of Hg pressure, ofabo'ut' 8.5 C; (15.3 F.) for'each unit change 1n carbon atoms per molecule'of the parafiinhydrocarbon. For other pressures the'boiling temference being about 40 C.'-for the C26 to C30 range, a carbon atom range of four,- or about loicppercarbon atom difierence.

" It will be seen from the foregoing, and byreference to Fig. I, thata'sharply cut, narrow boilin'grange distillate fraction of parafiinic hydrocarbons having an average boiling point within therange of from about'200 C. to about 340C and having a-boiling range of not over about40 C., or about 75 F., at times 45 0., at 15 mm. of Hg, will define a mixture of paraffinic hydrocarbons containing asparaffinic' hydrocarbons substantially only those which come within'a car-. bon atom range of four. Thus, such a distillate fraction having a boiling range of from about 258 C. to about 300 (at 15 mm. of-I-Ig) is restricted to paraffinic hydrocarbons which contain from 26 to 30 carbon atoms'per molecule, a carbon atom range-of four. For allpracticalpurposes, when dealing with petroleumfhydrocarbon mixtures the end temperatures of the various fractions may be considered to be the 10% and 90% over points, respectively, although for the wider boiling range fractions'fiour carbon atom range) it is preferable that the40 I 75 -F.')';range be more nearly*the 5%*and 95% overpoints, respectively. From-the foregoing, it

will be understood, for example, that when it is -'C. (or about "of more than .520 and up to, :for. example.

'6 that with .paraffinwax ;-mixtur es as normally found in petroleum, at higher molecularweights the fractions tend;to;.possess increased concentrations of isoparaffins so that melting-,pointdifferences-between the constituents become somewhat less, thus making it necessary to work-with ever decreasing sizes of fractions to obtain ma imu yields and maximum purities of end product waxes. Thus, .for :those hydrocarbon fractions which possessv an average 1 molecular weightof from about 400 to about 520, the boilinggoint range spread (10-90% :greater than about ..'75

distilled) should be no 'F. (about 40-45% 0. and preferably no greater :than about -65 F. (35 C.) while, withan average molecular, weight about 800, and containing upto about .60 carbonatoms about 40-50 F. (about 22-28" per molecule, ',{the...spread should be not rover 'C.')-, "and :preferably about-2091 to.25 .(about'll C. to .15. C.) for 10% to 90%"1'distilled, at 7 mm. of H and essentially: the same at '15 .mm. and:.50,;mm.

of l-lg respectively- .7 Thefractionation of thenarrow boiling range paraffinic waXy petroleum fractions into ,wax products according to melting points'to. separate substantially pure normal paraffin waxes .from

the non-straight-chain parafiinic hydrocarbons, and the coordinated .combination .thereofuwith the fractionation according to molecular weights or carbon content, will be morefully understood from tl re following description made with par- 'ticular reference to the melting point relationships "shown in. Fig. I. paraffin-hydrocarbons are strongly :dependent on ithe structuresof the hydrocarbons. .appears to be true particularly in the case ofzstruc- -turally different paraffin wax hydrocarbons, that The melting points of is parafiinic hydrocarbons containingzabout '16 -or.more carbon, atoms per moleculaand especially': those containing at .least 1 about 20 carbon desired to secure a distillate fraction of-paraffinic hydrocarbons containing as the-lowest any substantial amount,

a small amount below the boiling point of the 'Il-Czs paraffin, that is about260 boilingjpoint will be higher than 260 C. by a value of about 8.5 multiplied by n, n being the carbon atom range of the desired fraction. Of course, if the ,range is to be two carbon atoms, then the temperature range may be and preferably is,-a small amount greater than "twice 8.5, such as about 2.2 to 2.5 times 8.5, or from 18.7 to about 21.2, or about 20C. (about 35 F.) anyway a range somewhat less than the minimum 3 carbon atom range, say less than 42 F. or 23 0.; for a three carbon atom range, the temperature range is from about 3 to about 3.5 times 8.5, or from 25 to about 30 C. (from e5 F. to about 55 F.) intermediately about 28 0. (about F.) anyway less than say 34 C.

In connection with the relationships which exist between boiling range, carbon atom content range"and relative melting points of straightparaffin waxes,

C., and the end.

atoms per molecule. Thus, either branching or :ring-closure withinitan aliphatic (paraffin') hydrocarbon of the rangesindicated-is accompanied by ;a marked and significant drop in the melting point. It has been found that this difference -,is ;sufi iciently large such that the meltingpoint of ;a given n-paraflin wax hydrocarbon containing .11. carbon, atoms per molecule (n being at least about 16 and preferably '20 ormore) is still significantly higher than the melting points of the isoand cyclo-paraflin wax hydrocarbons which contain n+3, and evenn+4, carbonatorns per molecule, the difference being much more marked for n+2. This is more readily seen from the portion of Fig. I which shows therelationships between the melting points (as ordinates reading on the left side of the figure) and the number of carbon atoms per molecule (along the horizontal axis). The melting points for the straight-chain parafiin hydrocarbons are representedby the indicated solid curve, which is approximated bythe indicated straight dashed line, corresponding to the linear equation:'

e I iMelting po'int ('C.).=7.5+2.4n forintegralvames or n from about 20 to about '36, and wherein *n 'is the numberofgcarbon atoms per molecule of the straight-chain parafilnic hydrocarbon; Thus there is a change ofabout 2.4" C. in'melting point for a change of one carbon I atom 'per 'molecule.

Whereas 'th 're' only a -Sillg'le normal; parafiin hydrocarbon having-the formula 'C 'HM-l-g "for.

a given value of m; there"*are'-many' isomeric 7 branched-chain and cyclo paraffinic hydrocarbons having-the 'same' number of carbon atoms per molecule. The x points." in Fig. I arcindicative of the melting points ofsuch isomeric v pa'rafiinsthe melting points ofstill many others of said isomers being below 16-'C., the lowest point representable on the graph. In general, themelting-point of the highest melting isomeric paraffin is considerably lower than the melting point ofthe corresponding normal parafiin wax,

generally being at least about -15" C. In the case of actual natural mixtures the practical value maybe at least about 20 C., orabout twice as far below the melting point of said corresponding normal paraffin wax as the melting point of the normal paraffin wax which contains as much as four. carbon atoms per molecule less than said corresponding normal paraffin wax.

In thegraphin'Fig. I, various fractions are defined by vertical "dotted lines. Eachof the fractions sodefined covers approximately a;region rangingwfrom n to n+2, inclusive, carbon atoms, i. e., a range of two carbon atoms, range being defined as the difierence between the smallest and largest values of the variable (number of carbon atoms). Referring to the graph, itis seen, forexample, that the n-paraffin hydrocarbon containing carbon atoms per molecule has a melting point which is significantly higher than the melting point of the highest melting pointnon-straight chain paraffin hydrocarbon isomer '(i. e., isoor cyclo-parafiin hydrocarbon) which contains 28, or even 29, carbon atoms. It will be noted. further from the graphthat there are many more isomeric isoand cyclo-parafiins containing 25, 26, 27, 28 and even 29 :carbon atoms per molecule, whiclihave melting points still furtherrbelow the melting point or the ,25- carbon atom' normal paraffin hydrocarbon. These other isomeric paraifins constitute a large proportion of the total isomeric parafiin content of any actual petroleum distillate fraction of a petroleum oil stock containing both normal and isomeric paraifinic hydrocarbons.

Although the above-indicated differences in' melting points of paraflin wax hydrocarbons having boiling points "within a relatively narrow boiling range corresponding to a-carbon content range of not more than about four (4) "carbon atoms per molecule; make it possible to "separate such mixtures of paraffin wax hydrocarbons by a processor solidification and/or melting'based solely upon melting and solidification temperature diiferences, it is preferred to efiectsuch fractionation in the presence of a suitable solventor diluent. The solubility of a paraffin wax hydrocarbon in a solvent, for example, a polar solvent, such as oxygenated and/0r halogenated hydrocarbon derivatives (methyl ethyl ketone,

methyl isobutyl ketone, ethylene dichloride), and mixtures thereof, and also in admixture with hydrocarbons such as benzene, toluene, light petroleum hydrocarbons, and the like, is related to the'melting point of the paraflinhydrocarbon in the sense that the solubility becomes exceedingly low at a given temperature below .the solidification or melting point of the parafiin hydrocarbon, the given temperature being. dependent upon and correlated with the melting point' of the parafiin hydrocarbon and being substantially independent of the structural configuration of t the paraffin. ,Usually those solventswhich show anyselectivityexhibit greater solvent power for the isoand cyclo-paraflinic -hydrocarbonsthan T8 .fonthernormal para'fiins; hencei enhancing their utility'in the present-inventionfi 'y I. iz'Ilius; an advantage which :usually accrues fromgrithe-use' of,,o,rganic diluents or solvents which possess more or-less of solvent selectivity fonthe diifer'ent. types of paraffin hydrocarbons is that the :difference (spreadXbetween the solidifldation-temperatures (inthe presence of the solvent) of the lowest melting normal parafiinic wax-' and-the highest melting isomeric parafiim'c wax-in the'mixtureiis increased; This increased ldiiference between solidification temperatures -reduces:the 'critifcality' of the. temperature required for the desired separation of 'nfrom isomeric-paraffin waxes; in the mixture: I-Iowever, regardless of whether there is any-further spreadi o the solidif ti temperatures in itherpresence of a 'SOlVBIltythG respective solidification temperatures 'of the difierent waxes are lowered ..bB1QW' theirmelting points, because of the .solvency ofthe solvent. Thislowering is as 1111,1011 or more for;'tl 1 e isomeric parafiins as for the normal paraffins; In-general, inpractical operations, wherein;.i 2-; to 10,and preferably 5 .to'7', volumes of solvent, are employed per weight ofoiland/or wax; usingconsistent' units in the or g.- s. system-as cubic centimeters of liquid per gram of solid, a temperature of 30 to 40 C.below; the melting point ofa given parafiin wax molecular species insures almost complete insolubility of; that givenwax. I In; orderto show-how wella wax mixture may beseparated by fractional crystallization, a blend ofequal parts of three practically pure normal 'parafiin hydrocarbons was fractionally crystal- "1iZ8 d'ffI' Om methyl isobutyl' ketone. The hydrocarbons used-were: Q j i XIXno'rmaI Cz'z'His-M. P.= l5 C. (2) normal C2eI-I5 'M.-P.;56 C. (3)no rmal CaoHezi-M. P.=65.2 C. their individual solubility curves in methyl isobutyl 'ketone are shown in Fig. II. One part by -weight ofthisblend-was dissolved in 9 parts by-v/eight of methyl. isobutyl 'ketone and then -very s1owlycooled; The first wax crystals ap- :peared at 39. 0}, which is exactly the temperatur'e atwhich the pure CsoHsz wouldstart to crystallize if itwerealone in solution (as a 3.3%

again washed with 3.3- parts of solvent. After removing-the solvent 'from both the cakes and "the. final filtrate, the I following waxes 5 were ob- .jta'inedz Filter Wax Wax A i .Fraction 1.. 28 Y t Fraction 2 V 15 4 Fraction 3.... i Filtrate f0. 38 45. 8

. organic solvents 7 tures of representative straight-chain paraffin The efiect of the presence of representative on the solidification temperawaxes and;nonstraight chain -parafiin waxes is having the boiling 4 respective. curves. v bricating .oil. crude stock was toppedtolremove fractions having '-90% r C., 23 C., 13? 0., 23C., ar'1d 43 (1., respectively.-

showninjig. III. Referring to Fig. 111, the solubilities of such paraffinwaxes in methyl ethyl ketone, in methyl isobutyljketone and in toluene.v

at various temperatures, areshown by the indicated-curves. The two waxes referred to therein were obtained. from'a. higher'boiling distillate fraction'ofi a Mid-Continent lubricating oil stock and they had melting. points and average molecular weights as follows; (1) Crystalline 1.0. established; The melting points and refractive indices of the various fractions of wax thus separated are indicated in Fig. IV; ,It will be noted-that there is a linear-relationship between the refractive indices and' melting points of the normal or straight-chainparafiin waxes.- This relationship -may berepresented by theequation': i Index'of refraction v v (at '70 C.) =1.4074+0.0004 M. P. in C; Pertinent corresponding data'are tabulated be low. It is'readily seen from Fig. IV that'such a fractional crystallization on a' test portion of a, narrow boiling range fraction being processed commercially at once gives information as to the temperature at which the separation ofthe normal paraflfin waxes from the other waxes should be carried out to obtain the desired-separation; it is the temperature at which an equilibriumincrement of wax separated'thereat has the "lowest index of refraction of any equilibrium increment separated at any other temperature.

Wax fractionation of West Texas EZZenberger distzlldtesv Properties of Fraction I Total Wax in Fractions Crystalline-Wax 5; Per Cent Per Cent M. P. I Per Cent M. P; R. l.

FractlonNo. 10410, on Total 'Waxin Wax 70C Cryst. Wax 70 C or Dist. Fraction C. Wax .Wax Cl Wax g f 20.4 6.65 51.5 1.4306 .68.? .53 1.4308 355 19. 5 7. 22 54 -l. 4332 68. '5 T 58 1. 4326 380 I 19.8 7.15 56 1.4364 -57 62.5 1.4347 420 20. 0 7. 58 1.4409 34 68. 5 l. 4367 450 20.3 4. 95 65 1.4457 14 73 1.4438 ca. 500

tillate fractions of West Texas Ellenberger lubricating oil basestock, the, distillate fractions ranges as 'indicated on the A..West .TexasEllenberger luthe lighter, non-lubricating; oil. fractions, and then. five consecutive vacuum distillate fractions of lubricating oil were obtained by careful frac tionation in a fractionatingcolumn having the equivalent of four theoretical plates, the five boiling ranges of 17 The various, distillate cuts were then individually dewaxed completely at about g5 0.; with methyl ethyl, ketone or methyl isobutyl ketone in the usualway; ,It will belunderstood that the distillate cuts couldhave been solvent extracted with a selective solvent such as phenol or furfural prior to the dewaxing operation, without materiallyaffecting i the subsequent separation of the normal paraffin waxes from the non-straight-chain paraffin' waxes. 'Then: each wax portion "(containing the total wax present in a given distillate fraction) was separated by fractional crystallization as follows:

The waxwas-dissolved in methyl isobutyl ketone 10 parts per part :of

cooled until about 10% of "the wax had crystallized. The crystals 'werefiltered'off, dried and weighed" and the melting pointand the refracand filtered in approxi- By pmttmg the refracpoint of each "be" distinguished from non-straight chain waxcomponents and the yield. of both wax yp an-bewax' portion) and slowly As a comparison with the separations" as shown'in Fig. IV and described 'above',.another .portion of the same- West Texas Ellenberger topped crude was distilled under reduced pressure' an'd'three separate lubricating oil. stock distillate fractions were obtained, as indicated ion: the curves in V, namely, aiirst fraction having an average viscosity of K 100 SayboltUniversal seconds at 100 +F. and having -aboiling range of about 53 C., a secondrfraction having an-average viscosity of 250- SUS' at- 100 F." and having a boiling range of about67 G1, and a third-heavy distillate fraction comprising the remainder of the stock whichis distillable under normal plant vacuum distillation conditions without raising the temperature to cracking conditions, said fraction having a boiling range of about 95 C; Each fraction was solvent extracted and'the respective de-oiled waxes. were separately fractionallycrystallized from solurated, that is higher melting point, fractions tive. index at 'C. were determined. The-filof waxes were pure normal paraflinic hydrocarbons. For sake of completeness and clarification ofdifferences, the boiling curves of the distillate fractions indicated in Figs. IV and V are given in Fig. VI. I 1

' Similar separations of the hydrocarbon waxes .are obtained when other, portions of the same lubricating oil distillatev fractions are similarly fractionated, without prior separation of the; oil components from the wax components and even without'prior solventextraction, although it ispreferred to solvent extract the oil fraction prior tothe separation of the waxes since the solvent extractable -materials are more easily removed at this stage of the operation and it is easier thereby to produce waxes of better color and odor.

Having described the inventionin a general manner an'd having discussed various factors related to the invention, and their correlation in the application ofithe invention, it will be better understood from a more detailed description of amore specific embodiment thereof. A more detailed description will be made with reference, for example, to a so-called slack wax or crude wax, producedand obtained in the art and which is usually an oil'mass of, a mixture predominatingin parafiin waxes including both n-paraffin's and 3 isoand cyclo-paraffins, the proportions thereof depending on the nature of the petroleum stock from which the slack wax is obtained. 7 A

representative total lubricating oil distillate slack wax may have a boiling range of from about 180- F. to about 310 F. at 7 mm. of Hg. pressure, corresponding to from about 200 F. to about 330 F.

at mm. of Hg. pressure, and may have a range' for thenumber of carbon atomsper molecule of; C to C or C36 and generally will contain from,

about toabout 80% of wax and 20% to 60% of oil, the melting point of the wax ranging from about 90 3. to about 165 F., dependingonthe, relative proportions of'wax and oil and also on-j the relative proportions of the. various molecular;

species of wax molecules present.

h Now, the first essential 'step, in accordance" with the present invention, is to fractionate the slack wax into a number of fractions, at least one fraction of which, and preferably all of the fractions, contains parafiin hydrocarbon waxes which have a range of carbon atoms per molecule of not more than four and preferably not more 5 than two and three, such that the melting point of the highest melting isomeric parafiin'wax in said fraction 'is lower 'than'the melting point of the lowest meltingnormal parafiin wax therein. In general, it will be satisfactory if at least 90% of theisomeric paraffin waxes therein melts below the melting point of the lowest melting n-paraffin wax present therein. The separation of the wax content of the slack 'wax into the indicated fractions may be effected either with or without a prior separation of any or a substantial proportion of the oil content thereof. That is, the slack wax may be de-oiled by any suitable method; such 'as sweating fanld/orsolvent de-oiling, first to re- I move substantiallyall or a substantial proportion of the oil content thereof, to produce a scale wax "and the separated wax then fractionated, as by "distillation, into the desired fractions. -Alternatively, the slack wax may be fractionated into thedesiredfractionsfwith subsequent removal of the oil contents thereof, if desired. It is not necessary, n r even desirable in many cases, to

remove the oil content, its separation and/or re-' j covery being better effected in subsequent operations. It will also be understood from the previousdescription with reference to Fig. II, that the; total lubricating oil distillate stock may be 1 fractionated into the narrow boiling range fractions and that each such fraction may be processed according to the invention to separate the straight-chain paraifin waxes therein from the r other waxes, which other waxes 7 may also be recovered separately.

Now, assuming for clarity of discussion that the slack wax has been fractionated to produce at least one narrow cutslack wax fraction as defined above, the next essential step of the process isthe adjustment ofthe temperature of said fraction so as to insure the existence'of the normal paraffinwaxes therein-in a solidified. state and the existence of the isomeric isoand/or cyclo-paraffin waxes in a liquefied state, "or at least predominant proportions thereof, respectively, in'the respective states. The desired separation, as supplied to the indicated fraction, can now be effected by adjusting the temperature of separation so as to be between the solidification temperature of the lowest melting normal paraffin wax hydrocarbonpresent and thethe solidification temperatureof the highest melting isomeric parafiin hydrocarbon present, which temperature-of separation may be the same as or different from a temperature intermediate the meltingpoints, as already indicated for those cases when a solvent is present, then maintaining the selected temperature until the desired liquefaction and/or solidification has taken place (that etc, fractions, as well as various organic liquids such as halogenated hydrocarbons (chloroform. carbon tetrachloride, ethylene dichloride, ethyl- .idene dichloride, etc.) ethers (ethyl ether, ethyl propyl ether, methyl isobutyl ether, and the like), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aromatic hydrocarbons (benzene, toluene, xylene, and the like), and various mixtures thereof.

Thus, having adjusted thetemperature of the selected narrow but slack waxfraction, with or Without. the addition ofa suitable solvent, but

. preferably with the addition of a solvent such as a polar organic solvent or solvent mixture, with the resultant solidification of the normal paraflin waxes therein and/or the liquefaction of the isomeric paraffin waxes therein, the resulting mixture or slurry is's'ep arated, as by filtration or centrifugati'on or the like into a separated solid phase containing 5 the normal paraffin waxes therein and a separated liquid phase containing the] isomeric paraffinwaxes together with the solvent and/or-oiL' In thecase where hydro- -carbon oil is present in the separated liquid phase, this phase is preferably cooled to a'still lower temperature to solidify orprecipitate the isomeric paraffin waxes, which resulting micro- -crystalline'0r amorphous wax i then separated from the oil-and solvent.

In the absence of added solvent, the heavier substantially oil-free wax fractions require higher temperatures at which the separation of normal from isomeric parafiin waxes is effected; however, in the presence of a selective solvent not so high temperatures are required to effect the desired separation based on the precipitation of the normal paraflin waxes from the mixture 13 While maintaining the isomeric paraffin waxes in the liquid state.

It will be understood, particularly byreference to Fig. I, that a substantial separation, which may be entirely satisfactoryin some cases, depending on the initialwax material, the desired wax products, etc., may be accomplished by minor deviations 'from the above indicated combination of operations. the case wherein the selected narrow cutof wax fraction contains, say C25 through'C'zs'paraffin Thus, rte example, in

14 a normal paraffin wax product, an isomeric paraflin wax product and a slack wax with a melting point of'about. 130 F. and an oil content -of about taken from a storagetank-l |j;-provid ed with asuitable heating means as 112-, at a temperature slightly above the melting point thereof, is transferred 'through'a' line l4=to a mixer l5 wherein it is mixed with about 115 parts byweight ('all relative parts are based on a unitpart by weight' of charged slack hydrocarbons, and in which, for example, the

straight-chain hydrocarbons are about 90% C2 C27 and C28, a satisfactory yield'of the straightchain paraffin wax will be obtained even when theseparation is effected at atemperature at and non-straight chain paraffin waxes may acr.u ally be belowthe temperature at which the high est melting non-straight-chain 'p'araflin', wax

present therein solidifiesunder the conditions of the operation and still satisfactory products will be obtained. Similarly; as will be'seen from'Fig. I, a slightly wider range fractions maybe re solved into satisfactory straight-chain and nonstraight chain paraffin wax products by applica tion of the invention, even in those cases where.

the melting pointof the lowest melting normal wax is not necessarily above the melting point, of the highest melting isomeric-wax therein prQ- vided the, resulting overlapping of melting points does not involve more thanabout ten per-. cent, preferably not more than five percent, of the total paraflin wax content of the fraction involved, or not more than about ten percent based cipitating substantially only and yet substaningsfrom a subsequent second stage precipita of solvent-oil-liquefied isomeric parafiinfis trans-' on the normal paraflin wax content thereof.

Thus, in general, the selection of a range of the paraflin wax hydrocarbons for a given fraction and/or .the selection of asuitable temperature for separation of the normalfromthe isomericparaffin waxes therein are correlated so that the paraffin wax content of oneof the separated products will be such that the ratio of the weight of one of the types of parafiin waxes therein .to the other type willbe atl'east about 90 to 10, that is, 90% purity. on the wax basis with respect to either the normalor the isomeric-paraffin Wax. v The following description of a preferred embodiment of the invention, made with reference to Fig. VII of the accompanying drawing which forms a part of the specification, will give a better understanding of the practice of the invention andwill indicate the correlations between the various operations ofthe process. Referring to Fig. VII, it is seen that by the designated COIllbination of operations, a narrow cut (narrow boiling range) slack wax. (which was obtained as a narrow boiling range cut -from distillation of a wide boiling range East Texas 250 neutral slack wax material having a melting range of 130-135 F. and containing'about 10% of oil) is separated by a combination of crystallization and separation operations at F. and -15 F. into sultingmixture of slack wax and processing.

wax) 'of a a "70230:" by volume solvent mixture of methyl ethyl ketorie and benzene introduced'into the line H through a solvent line l6.- The 're- I solvent isthen transferred through a line 1 to a series of double pipe chillers I9, 20 and 2|, through which the mixture passes out of contact with, but in heat interchange relation to, a cooling means, which in this case is refrigerating ammonia delivered thereto'by means of lines 22, 24 and'25 provided with suitable expansion valvesor the like and connected with a common liquid ammonia line 26, which, in turn, is partof the cyclic system including return line 23 and suitable compressing and cooling means as indicated by 28 and 33. The slackwaX-solvent mixture is thus cooled to a temperature of 50F. (which temperature is determined by an independent experiment as described hereinafter to be suitable for pretially allof 'thenormal'paraffin waxes from the given mixture). Just ahead of-the last o'f the three stages of the chilling operationas repres'ented by chillers |9, 20 and 2|, that is, --just 'aheado'f chiller 2|, another 1.5 parts of solvent' mixture (which is made up of filtrate and washtion and filtration operation) is added by means of a line 21 to the partially chilled slack waxsolvent mixture.- The resulting slurry of solidified n-paraffin wax suspended in the liquid phase ferred through line 29 to a surge tank 30 (which may be provided with any suitable agitating and cooling means) from which the slurry is transferred to a suitable phase-separating means such as a rotary filter 3|. The slurry is' filtered at a temperature of 50 F. with the filter cake being washed with another 1.5 parts of solvent mixture delivered to the filter through a" line" 32.

The'mixed filtrate and wash solvent, amounting to 4.5 parts (per part of charged slack wax) are collected linfa tank 34'-"forfurther subsequent The waxca'ke frornlfilter-3 l, containing a small proportion of retained" solvent and oil, is transferred byfls' uitable-means to a slurry mixing and surge tank-:35, provided-withsuitable agitating and cooling means, wherein it is re-slurrid with 1.5 parts of solvent mixture from-line 33, coole d to '50 F. by suitable cooler 3; i This slurry at"50 F. is then transferred to a filter 21 wherein it is filtered and washed, the filtrate being collected in a vessel: 38 and.the wash' liquid being'collected in a;vessel 39.; The recoveredwash liquid is transferred throughline'32 to filter- 31 for use therein as, already discussed; The wax cake' is transferred from filter '31 by suitable means, indicated by line "40, to. suitable product waxstorage "4| for the normal parafiin wax, the recovery being about (based on total, charge stock). for the particular slack wax cut chosen. *The n-paraflinwax had a melting point of about F. .Any solvent remaining therein may be recovered by any dewaxed oil product. More specifically, a narrow boiling range cut of suitable means, as .willbeunderstood in the art,

andTeturned to :solvent-storager lzvby. means.- of

lines and 45.

Now; returning the" filtrate and washing 7 mixture from-:filter 3 I,- awhich rmixture contains the" isometric iso-rand 'cyclo parafiin waxes and the;oil contentsiof; the slack wax charge in solution-admixture with-v 4.5 'parts of solvent, ;this mixtureis transferred-by-line -5l' to a series of; I doublepipe heat exchangers;52,=54 and 55 wherein the mixture is, cooledserially and finally to a suitable temperaturefor precipitating the isomeric .paraffin .waxes, :or'to a temperature which is selected toyield a dewaxed oilfraction having adesired pour point; inthe present'case to a temperature of 15 F; The chilling in thefirsttwdof the heat exchangers '(52 and 54) is eifec'tedby heat exchange against the chilled. filtrate I from filtration at 15 F.-of a preceding portion ofthesame mixture while thelast stage of the chilling' crystalline oramorphous), istransferredthrough line 51-to a surge tank- 59;which'maybe providedwith suitable agitating and cooling means as: 60

and BI respectively, maintained-at--155F. 1 The slurry is transferred from surge tank 59 bymeans ofa line 62- to a suitable solid-liquidphase-sepaa rating-means such. as a rotaryifilter;64;.-whereinthe: slurry is-.filtered atw1'5 F.'to yielda filtrate which --is delivered toa storage -vessel1B5.-: Three.

and ;one ha1f parts of. this filtrate is deliveredthrough lines'66 andfi'! to the heatexchangers 52; and 54 and thence to a dewaxed' oil.storagerfiil r from which the solvent is removed by any suit-' able means and-returned by lines Wand-A5 to solvent storage '42; The dewaxed oil recoveryfor the particular case used amounted to about based onslack wax-charge.

The filter cake of isomeric paraffin waxes-in filter 64 is washed with-0.5 part or" fresh, chilledsolvent mixturetaken from storage 42- and chilled to F. in a suitable cooler -1|-, the washings being transferredto-storage tank--12." The washings from this operation; together withone part of filtrate from filtrate storage 6 5- are; delivered through lines 14, 66 and 16 to alineld for ad-" mixture with a subsequent portion of slackwax charge. Thewashedfilter cake is removed from filter 64to a soft wax storage 15,- via line 16, the small proportion of solvent therein being -re-' covered by-lany suitable means andreturned to solvent storage 42through-lines=11 and-45. The soft wax recovery, that is, themixture of microcrystallineor amorphous isomeric parafiin waxes, foethisca'se amounted toabout 25%, based on the slack wax charge. I I 1 It will-be understoodthat various modifications of theabove-describedprocess will be 'made' in processing different waxmixtures in accordance with the present invention,- Thus, for the difier ent-narrow boiling range 'cuts of the above 'described wide: boiling range slack .wax material, the -first f temperature of separation of normalfrom-isomeric paraifin waxes will'v'ary depending on gth'e particular out being processed. 'The' first separation temperature will be higher the higher the boilingpoint range of the wax fraction. On the othlerrhand, the second separation temperatureyi. e., the temperature at which'the isomeric paraflinitwaxesaare. precipitated from solution;

may. be the same for-thelvarious fractions, such. as 10 F. down to 40 F. In fact, if it is desired, the filtrates from the first-temperature separations may-be,.-combined-and treated .to-

gether to effect-- the second-temperature separation. It will be, understood further,- of course,

that various blendcombinations of the separated waxes maybe made .to yield wax .blendswith desired characteristics. As already indicated, various diluents and/ or selective solvents may be used in place of the-methyl ethyl ketone-ben2ene-sol vent usedin the foregoing illustrative example;

or the separation .may beeffectedwithoutany added solvent in some cases.- Further; in; the case of an oil-containing wax, such asslack wax; the narrow cut oil wax -charge may first be subjected to V a I very low temperature, suchas the 1 5 F. of the foregoing illustration,- or 'eventolower-temperaturessuchas 40v F., more or'less; alone or, preferably, in the presence of a suitable-- diluent and/ or selective solvent, whereby the nor-' mal as well as the isomeric parafiin waxes precipv separated from the isomeric paraifinwaxes in solution .in .thesolventand/or in vthe liquefied:

state. 7 I

The presentinventionis applicable to the treat ment of various. types of parafl'inic wax-mixtures, including slack waxes. (as described above), slop waxes, scale waxes short and longiwax residues as obtained by processes well. known to. the art-, etc. The fractionation .of-.@the..wax. mixture into the required fractions to be processed in.accord-- ance with the inventionmay be madeby -any suitable method, such as by distillation, preferably underv reduced pressure, and with orwithoutan. added extraneous (carrying agent. .Inl the frac.-.. tionation, suificiently .narrow rangeof molecular. weights and of the corresponding boiling, points in a cut may be tested empirically by a small-. scale testonan aliquot part of th cut, insolution with a suitable solvent, tode'termi'ne-that when the resulting solutionis cooled appreciably below themelting point of the lowest-melting n-paraffinwax therein, there is substantially complete separation of the n-p-arafiin Wax therein from the non-straight chain waxes in the cut. Tests upon the resulting separated wax to show the structural character of the wax are readily made by persons skilled in the art making use of such conventional tests as that for ring value and for asymmetric value. In addition to advantages already referred to which accrue from the practice of theinvention, other advantages will beapparent to thoseskilled in the art from the foregoing description of .the invention. For example, as indicated in the proc-, ess described with referenceto the accompanying drawing, an important advantage derived from the fact that relatively much smaller proportions of solvents may be used than are nor-' mally required in the processes as generally used in the art. Thus, as indicated in the illustrative example, as little as four parts of solvent maybe used per part of slack wax. Oi course,'it will be understood that the ratio ofsolvent to waxy material may be varied over relatively wide ranges for the various operations, and depending on the nature of the solvent, the proportions of thedifsolvent the refrigeration requirements are greatly reduced. Another advantage lies in the fact that no great demand is made upon the selectivity of the solvent, although, as statedhereinabove, solvents with greater selectivity for the waxes produce a greater spread between the solidification temperature of the lowest melting normal parseparating the noraflinic wax and ofthehighest melting isomeric paraflinic wax present in a given narrow range cut of waxes in the presence of said solvent.

Various modifications ,of the hereinabove-described techniques of manipulation as are known in the. art maybe utilized in the practice of the invention. Thus, the separation of solid'from liquid phases may be eifected by pressure filtration, vacuum filtration,centrifugation, etc. The

cooling operations effecting waxcrystallization;

may be stepwise, if desired and also with or without .shocki chilling with stepwise introduction of super-cooled diluent and/ or selective solvent so as to effect a control over the crystal formation.

This application is a continuation-in-part of copending applications Serial No. 744,603; filed.

April 29, 1947, andSerial'No. 772,638, filedSeptember 8, 1947, both now abandoned. I claim as my invention:.

1. A process for the separation of straight chain paraffin waxes from paraifinic waxy mix tures containing both straight-chain paraffin non-straight chain paraffin waxes in waxes and the range of C20 to C hydrocarbons and wherein there is an overlapping of the-meltingpoints of the two types of waxes present, which process comprises the steps of separating from said Waxy mixture a plurality of narrow boiling range disf tillate" fractions at least one of; which contains both straight-chain and non-straight-chain paraffin waxes; has a boiling pointrange of not,

hydrocarbon waxes J which more than 40" C., and contains as straight-chain parafiin, waxes only differ by only four carbon atoms per molecule (On to Cn+4), whereinnt is an integerof from about 20 to about 35, and as non-straight-chain paraffin waxes only isomers of saidstraight-chain paraffin waxes, whereby the melting point of the lowest molecular weight (Ci) straight-chain parafifin wax present is higherthan the melting point of I the highest melting (0 1m) non-straightchain paraffin wax present therein; adjustingand maintaining the temperature of said distillate fraction at a temperature below the melting point of the 'Cn-straight-chain paraffinwax present and at which substantially all of th straight-chain paraffin waxes present is in the solid state but above the temperature at which any appreciable amount of the non-straight-chain paraiiin waxes separates as solid material, therebyproducing a solid phase of substantially allof the straightchain paraffin waxes presentinsaid fraction' and I substantially free from hon-straight-chain paraf-- fin waxes; and separating said solid straightchainparaflin waxe's'from the liquid phase of said non-strai'ght-chain para'flln waxes': a

atoms per molecule chain paraffin waxes from a paraniniciwaxy mix,- ture of straight-chain paranin waxes and nonstraightchain paraffin waxes at least some 10f whic'hstraight-chain paraffin waxes have melting points below the meltingpoints of at least.

some of said non-straight-chain paraffin waxes-.-

present therein, which process, comprises: separating fromi said waxy mixture by. distillationa" plurality of distillate fractions each of whichhas a boiling point range of not more than about: contains both straight-chain; paraflin-ri waxes and non-straight-chain parafiin waxesyz and the number of carbon atoms per molecule .of ,1 all of theparaflin waxes present therein differsby'no more than four'carbonatoms, whereby the: melting point of the' lowest melting straight-4v chain paraffin wax present'in'a given one of said fractions is higher than the melting point of the i highest melting 'non-straight-chain parafiin Zwax present in the same fraction; intimatelyand separately mixing each of said fractions. with =:ai

non-viscous diluent whichis non-reactive with-:- the temperatures of v the resulting mixtures thereof to temperaturea' said waxes and adjusting respectivleypwhich are below the melting points oi the lowest melting straight-chain: parafiin;

fractions and at whichv: waxes present-thereirr' waxes in the respective the straight-chain paraffin are substantially insoluble but substantially'all:

waxes present therein of 1 the other" parafiin v exist as a liquid phase withsaid diluentgthereby producing precipitates from each of said fractions"; of substantially all of the straight-chainparaffin 3' waxes present therein, respectively, as substan--'.. tially pure straight-chain paraffin waxes. and"; liquid phases of all of the other parafiin waxes: with the diluent; and separating the precipitates from the respective liquid phases. 3. A process for the-separation of straightchain paraffin waxes from paraffinic waxy mixi fz tures containing both straight-chain "paraffin waxes and non-straight-chain paraffin waxes in the range of C20 to C35 hydrocarbons and wherein there is an overlapping of the melting points'of the two types of waxes present, which process comprises the steps of: separating from said waxy mixture a plurality of narrow b'oiling range distillate fractions at least Qne'pr which contains'f both straight-chain and no'ri straight-chain par v afiln waxes, has a boiling point range oi -less than 23 C. at 15 mm. of mercury pressure, and contains as straight-chain paraffin waxes only hy=' drocarbon waxes which differ by only two carbon (Cn mo wherein'n' is-an' integer of from about 20' to about 35, and as non-- straight-chain paraffin waxes only isomers of said straight-chain paraffin waxes, whereby the rnelt ing point of the lowest molecular weight (010* straight-chain paraflin" wax present is higlier than the melting point ofthe highest. melting non-straight-chainparaffin wax present therein; adjusting and maintaining the temperaturebf said distillate fraction ata temperature below the melting point of the Cn straight-chain par- :5 afiin wax present and at which substantially all: of the straight-chain paraffin waxes present .are i in the solid state but abovethe temperature at' which any appreciable amount .of 'the .IIOIi-i:

straight-chain paraffin waxes separ tes as solid material, thereby producing a solid phase of isub'L- stantially all of the' st'raight chain' paraffinwaxes; present in said fraction and substantially :free'. from non-straight-chain par'aflin Jwaxes: iandy.

separating saidsolid straight-chain i parafiini 7, [9T rwaxesr from the-liquici phase of said non-straightchain -parafiin waxes;

41 A process forithe separation of straightchain parafiin' waxes from non-'straighFcha-in 1 paraflin waxes-in an oily slack wax stock having aboilin'g range o'f from about 180 F. to about 3109 F. at 7'mmso f Hg -pressure andhc'ontaining paraflinic waxes ranging'from about C'zoito about Csa-whichprocess comprisessubjectingsaid slack s wax to fractional distillationv under reduced pressure to produce -at least onei-fraction 1 therefrom havinga boiling pointrangeaofnot more than, about 40 C and;containing:only-hydrocarbon oil and both 'straight-ichaini hydrocarbonwaxes-land nonestraighti-chain L'hyclrocarbon r waxes, the number i of Icarbon atoms per moleculezof zall 10f whichwaxes I are present difiers by no more than. four' carbon atoms; intimately mixingsaidiraction with: a. non-viscous diluent which? nonreactive withsaid waxes sand-adjusting the stems-* perature of the mixture: to axtemperatu-re below the imelting pointof thelowest melting straightchain' p'aramn wax presentyand at which sub- 7 equilibrium-increment of wax which is separable from theparticular mixture at any other ternperature; thereby'producingjseparateprecipitates stantially :all of theistraight-chain parafiln'waxes present: therein arerinsoluble but substantially all ofihe'non-straightechainparaflin waxes presentltherein exist as ,a' liquid phase withsaid diluent'fand the oil,:.thereby producing; a precipitate of substantially all "of the straight-chain paraffin waxesipresent thereinlxas asingle fraction of straight-ehain-paraffin Waxes and a liquid phase of substantially allot the non-straight-chain.

paraflin' waxes withthediluent and oil; separatingstheprecipitate from the liquid phase; chilling the separatedshould-phase.to a still lower tern?- perature :sufilciently low to precipitate a substantial proportion: of the non-straight-chain parafiiniwaxespresent1 therein" without precipitating any of the ;-hydrocarbon-;oil present; and separating the;v precipitate of: non-straight-chain paraflim waxes; I from -the-remaining;solution= of diluent and-oil. I

5. :A- process; :for 'the'separationof straight.-

chain parafii-nrwaxesfrom:paraffinie waxy tures.:=ciontai-ning both straight-chain paraffin. waxesand;- non-straightrchain parafiin .waxesl and whereinthere is .anoyerlapping ofthe, meltingii'points oi thertwo- -types of-waxes present} whichprocesscomprises the -steps of separating boiling; ranger, distillate, fractions having boiling 50 from; said, waxy mixture V a-plurality oi; narrow rangesiwhich .arenot greaterthanabout 34 C. at

15tmmrof mercury pressure'and each of which contains :both. straightechain: and non-straight chain parafiin waxes, each of whichcontains-as straight-chain paraflin waxes {substantially only, hydrocarbon. Waxes which diff er by no lmore than threejcarbon atoms per molecule (C11, 7 to :C i+s,.

wherein is an integer of atleast-about. 20 andrasanormally solid-non-straight-chain paraffin V waxes-ionlyisomersof said straight-chain paraffin waxes. whereby the melting; point I of thelowest molecular: weight (C11,) straight-chain paraffin waxV.-prese n t:-i n a .givenfraction is higher than V the .y meltingnpoint of the. highest melting: non. v

straight-lchain paraffin wax present in the a same fraction; intimately; andseparately mixing said straights'chaimparaflin waxes and said normally solidmomstraight-chain paraifinwaxes in each of-fsaidafractions; respectively, with a nonrviscous diluentuwhichis non-reactive withsaid waves;

specti'vely, ;at which all of; the normal parafiin hydrocarbons present are substantially-insoluble separately. adjusting-the temperatures of-the re- 'spe'citive v resulting {mixtures to temperatures, re-

but: above the highest -temperature-, at-which any; appreciable-amount" QiisOmeric paraifins present therein: separates as:solid' material, said tempera tures being; respectively, those at which an; P equilibrium increment of wax separated therefrom his thef; lowest index-0f refraction of any;

of substantially all of the {straight-chain paraffin waxes :presentin the-srespective 1 fractions-sub; stantially-Jfreefrom isomeric hydrocarbons and solutionszinthe diluent of the. isomeric hydroca'r-e bons; andiseparatingtheprecipitates of straight chain paraifin waxes from :therespective solutions of diluent'and isomeric hydrocarbons.

'6'. A process in-accordance'withzclaim fi where in the distillate fractionsx haye boiling'i ranges: no greater tha'n about=23 C.' at*l5 mm. of mercury pressure.

7. A process for the separation ofstraightchain paraffin waxes from parafiinic waxy mixtures containing both straight ch'ain' 'parafiin' waxes and non-straight-ch'ain paraffin waxes in the- 'range of C20 to Che-hydrocarbons and wherein there is 'an'overlapping of 'the meltingpointsof the two typesof waxes 'present; which process? 7 comprises thesteps 'oifi separating fromv said waxy mixture a plurality ofnar'row boiling ranger distillate fractions each :of which hasl'aJboiling range which is vnot greater than about 45 C. at

15 .mm. of mercury pressureia'nd at least 'onefiof which contains both straight-chain. and nonstraig'ht chain paraffin waxes, has a boiling range .1: of less-than 34 "C. at15r'mm. of "mercury pres-, sure, and contains as 'straighti chain paraiiin waxes substantially only; hydrocarbon waxes which 'difier'by no more-than'ithree carbon atoms per molecule (Cit-to CH3 ,1 where n is-"an integer of from about: 20 to" ),,and as normally solid ncn-straight=chain parafiln :waxes only isomers of said straight-chainparailin Waxes.- whereby. the melting point of thelowest molecular weight (Cn) straight-chain parafiin waxpresent ishighervthanthe meltingp'oint-of the highest melting-now straight-chain parafi'in Wax" present therein; in-

timately mixing said normal paraffin hydrocarbon waxesandsaid normally solid non-straight-chain. paraflin waxes in saidli'i, Cr-boiling-range-frac-r, tion with a non-(viscous'fdiluent 'whichis .nonreactive with said'waxes'; adjusting the temperature of the resultingfmixture to a temperature 1 at which all of lthe normalpara fiin hydrocarbons present are substantially'insoluble but above the highest temperature at which any appreciable amount of isomeric paraflins p'resenttherein separates as solid material; said temperature being thatat which'an equilibrium increment of wax separated therefrom has the lowest indexof refraction of' any equilibrium increment of [wax waxes 'from the 30111171011101 diluent and isomeric hydrocarbons.

8. ,A- process for the separation of parafiin waxes from a parafiinic waxy mixture which con-' tains both straight-chain'paraflin waxes and nonstraight-chain parafiin wax isomersthereof having a boiling range at least'substantially'corextensive with the boiling range of; said straightacosjbeo 1 carbon atoms per molecule of the parafiin waxes present therein differs by no more than four carbon atoms, whereby the melting point of the lowest melting straight-chain paraffin wax pres ent in a given one of said fractions is higher than the melting point of the highest melting nonstraight-chain paraflin wax present in the same fraction, said fractions beingselected so that the lower boiling fraction of the two contains straight-chain paraffin waxhavinga melting point lower than the melting point of at least a portion of the non-straight-chain paraffin wax present in the other fraction; intimately and separately mixing each' of said two fractions with anon-viscous diluent which is non-reactive with said waxes and-separately adjusting the temperatures of the resulting mixtures thereof to temperatures, respectively, which are below the melting points of the lowest melting straightchain paraffin waxes in the respective fractions and at which the straight-chain parafiin waxes present therein are substantially insoluble but substantially all of the other parafiin waxes present therein exist as a liquid phase with the,

oil and said diluent, therebyproducing precipitates from each of said two fractions of substantially all of the straight-chain paraffin waxes present therein, respectively, and liquid phases of the other parafiin waxes and the hydrocarbon oil with the diluent; separating the precipitates from the respective liquid phases; combining at least substantial portions of the two separated a liquid phases; cooling the resulting mixture of liquid phases to a temperature at which a substantial proportion of the non-straight-chain paraffin waxes present therein precipitate, includ ing waxes from both of the liquid phases which were combined, thereby producing a second precipitate consisting essentially of non-straightchain paraflin waxes, and separating said second precipitate of non-straight-chain paraffin waxes from the remaining liquid phase.

9. In a process for dewaxing a waxy mineral oil which contains both n-parafiin hydrocarbon waxes and isomers thereof extending over therange of 020 to Gas-hydrocarbons, which isomers present and at which the n -paraflins therein-"are" substantially insoluble butabove the'temperature. at which any appreciable amount of isomeric parafflns therein separates as solid material, said temperature being that at which an equilibrium increment of wax separated thereat has the lowest index of refraction of any equilibrium increment separable therefrom at any other temperature, thereby producing a precipitate of substantially all of the n-p'arafiin" waxes present in said fraction substantially free from isomeric hydrocar bons and a solution in said solvent of the remaining portion of said fraction; and separating the precipitate of n-paraffin waxes fromthe solution of solvent andisomeric hydrocarbons.

- 10.-In a process for dewaxing a waxy mineral oil which contains both normal paraffin hydrohave a boiling range at least substantially co-' extensive'with the boiling range of said n-paraffin hydrocarbon waxes, the improvement whichcomprises the steps of: separating from said waxy,

mineral oil a plurality of narrow boiling range distillate fractions at least one of which has a boiling range which is not greater than about 45 Cl-at '15 mm. of mercury pressure and, contains as normal paraifin waxes only C11. to Cain-normal paraflin hydrocarbons, wherein n is an'integer from about 20 to about 35, and as other parafiin hydrocarbons only isomers thereof, and the melting point of the (Tn-normal parafiinhydrocarbon present is higher than the melting point of the highest melting isomeric hydrocarbon present;

intimately mixing said fraction with'a solvent proportion of a polar solvent for paraffin hydro carbons; adjusting the temperature of the resulting mixture to a temperature below the melting point of the (In-normal paraffin hydrocarbon carbon waxes and isomers thereof extending over the range of C20 to Gas-hydrocarbons, which isomers have a boiling" range at least substantially co-extensive with the boiling range of said normal paraffin hydrocarbon waxes, the improvement which comprises separating from said waxy mineral oil a plurality of narrow boiling range distillate fractions' each of which has a boiling range which is not greater than about 45 C. at 15 mm. of mercury pressure and each of which fractions contains as normal paraflin hydrocarbons only those which difier by no more than four carbon'atoms per molecule, and as other parafllns only isomers thereof; intimately mixing each of said fractions separately with a solvent proportioniof a solvent for said fraction of paraffin hydrocarbons; separately adjusting the temperature of each of said-resulting solvent-oil mixtures to a temperature below the melting point of the lowest melting normal paraffin hydrocarbon present therein and at which said lowest melting normal paraflin hydrocarbon is substantially insoluble in the solvent present but above the temperature at which any appreciable amount of isomeric paraffins therein separates as solid material, said temperature being that at which an equilibrium increment Of wax separated thereat has the lowest index of refraction of any equilibrium increment separable therefrom at any other temperature, thereby producing precipitates of substantially all of the normal paraffin waxes in the respective fractions and solutions in said solvent of the remaining portions of said fractions; and separating the precipitates of normal parafiin waxes from the respective solvent solutions of isomeric hydrocarbons. i

11. In a process for dewaxing a-waxy mineral oil which contains both normal paraflin hydrocarbon waxes and isomers thereof extending over the range of C20 to Gas-hydrocarbons, which isomers have a boiling range at least substantially co-extensive with the boiling range of said normal paraflin hydrocarbon waxes, the improvement which comprises the steps of: separating from said waxy mineral oil a plurality of narrow boiling range distillate fractions at least one of which has a boiling range which is not greater tains' as normal p'araflin'hydrocarbons substani tially'only C1 to Can-normal parafiin hydrocar-- bon; wherein n is'an integer of from about 20 to 4 about 35, including the czs-normalparaifin, and

as other parafiins only isomers thereof, and the melting point of the Cn-normal paraflln 'hydro- 1 carbon present is higher than the melting point of the highest melting isomeric hydrocarbon present;.- intimately mixing; said fractiomwith a solvent. proportion of a' polar solvent -for said fraction oil hydrocarbons; adjusting the temperature of. the resulting mixture; to a temperapresent therein -separates. as; solid material, said,

temperature; being that'at which an equilibrium incrementof wax separated thereat has-the lowestqindex of refractionaofmany equilibrium increment separable therefrom at any other temperature; therebyproducing a precipitate of sub-- stantially all of the n-parafiin waxespresent in said fraction-substantiallyfree from isomeric hydrocarbons and a solutionin said solvent of'the remaining portion of said fraction; and, separating the precipitate of normal paraffin waxes from the solution of solvent and" isomeric hydrocarbons. I 12. In a-process'for dewaxing awaxy mineral oil which contains both normal paraffin hydrocarbon waxes and isomers thereof in the range of C20 to Cass-hydrocarbons, WhiCh'iSOmGIS have a boiling range at least substantially co-extensive with the boiling range of said n-paraffin hydro-. carbon waxes, the improvement which comprises thefsteps of: separating from said waxymineral oil by distillation a plurality of distillate fractionsat'least one of which has a boiling rangeof about 28 C; at.-. 15 mm. ofv mercury pressure, whereby said fraction contains as normal parafiin'waxes substantially only Cn'tO Cum-normal paraffinqhydrocarbons wherein n is an integer from about 20 toiabout 35, and; as non-straightchain parafiins substantially only isomers thereof'and the melting point of the cn-normal paraffin hydrocarbon is higher than the melting point of the highest meltingisomeric hydrocarbon present;' intimately mixing said fraction with a polar solvent for paraffin hydrocarbons; adjustingthe temperature of the-resulting mixture to a temperature below the melting point of'the Cn-normal paraffin hydrocarbon-present and at which the n-parafiins therein'are substantially insoluble but above 'the te-mperature at which any appreciable amount ofisomeric parafiins' therein" separates as solid material, thereby producing a precipitate of substantially all of the normal parafiin waxes present in the given frac- 7 tion and a solution in said solvent of theremainingportion ofsaid givenoil fraction; and separating the precipitate of n-paraifin waxes from the solution of solvent and isomeric hydrocarbons. 5

-l3.-In-'a process for dewaxing a waxy mineral oil which contains both normal parafiin-*-hydrocarbon waxes and isomers thereof extending over the range 'of C20 to Gas-hydrocarbons, which isomers have a boiling range'at least'substantiallyco-extensive with the boiling range of said" normal parafiin hydrocarbon waxes, the improve ment which comprises'the steps of: separating from-said waxy mineral oil a plurality of narrow boiling range:distillate-fractionseach of which has a-boiling range-which is, not greater'than about C. at 1,5 mm. ofgmercury pressure and at least one of'which hasa boiling range which is about 20 C. at 15 mm. of mercury pressure and contains asnormal paraifin waxes substantially only C11 to Can-normal,paramnhydrocarbons, wherein n is an integer-from'about 20 to about-35,;and as normally solid non-straightchain paraffins substantially only isomers of said normal paraifin hydrocarbons'and the melting,

point of the Cn-normal paraffin hydrocarbon present: is higher than-the melting point'of the highest melting isomeric hydrocarbon-present;

dissolving the normal paraffin hydrocarbon l waxes and the normally solid non-straight-chain parafiin hydrocarbons present in said 20? C.-boiling-range-fraction in a solvent proportion of apolar solvent therefor; cooling theresulting solution to a temperature atwhichall of the normal paraifin hydrocarbons present are substantially insoluble but above the highest temperature-at which any appreciable amount of isomeric parafiins therein separates as solid material, said;- temperature being that at which an equilibrium;

increment of wax separated thereat hasthe lowest index of refraction of any equilibriumdn-q crement of wax which-is separable fromsaid' solution at any other temperature, thereby pro-- ducing a precipitate of substantiallyall of the n-parafiin waxes present insaid fraction substantiallyfree from isomeric hydrocarbons and a solution in said solvent of isomeric paraflin hydrocarbons; and separating the precipitate of normal parafiin waxes from the solution vent and isomeric hydrocarbons.

141 In a process for dewaxing a waxy mineral of sol- (go-extensive with the boiling range of said nor.- mal parafiin hydrocarbon waxes, the improvement which comprises the steps of: separating from said waxy mineral oil a plurality of nar row boiling range distillate fractions each of which has a boiling range which is not'greater than about 45C. at 15mm. of mercury pressure,

and at least oneof which hasa boiling range which about 20 C. at 15 mm; of mercury -pres-" sure and contains as normal para-mm waxes sub-5 stantially only Cu to Cn+z-normalparamn hydrocarbons, wherein n is an integer from about 20 to about 85,and as non-straight-chain paraffins substantially only isomers of said normal paraffin hydrocarbons, and the melting point of the Cnl'lOI'l'flQl parafiin'hydrocarbon present is higher than the melting point of theyhighest melting isomeric hydrocarbon present; intimately mixing said fraction with a solvent proportion of a polar solvent for said fraction of paramn'hydrocarbons; adjusting the temperature of'jthe resulting mixture to a temperature below the melting point offthe (tn-normal paraflin hydrocarbon present and at which the normal parafiins therein are substantially insoluble but abovethe temperature at which any"appr.eciable amount of isomeric parafiins therein separates, as solid material, thereby producing a precipitate of substantially all of the normal paraflln waxespresent in said fraction substantially free-from iso-- meric hydrocarbons and a solution in said solvent of the remaining portion of said fraction; and separating the precipitate of normal parafiin waxes from the solution'of solvent and isomeric hydrocarbons.

15. In a process for oil which contains both normal parafiin'hydrocarbon waxes and. isomers'thereof extending overthe range-of C20 to Cat-hydrocarbons, which isomers have a boiling range at least substantially co-extensive with the boiling range of said normalparafiin hydrocarbon .waxes, the improve,

ment which comprises the steps of: separating dewaxinga waxy mineral 25 from said waxy mineral oil a plurality of narrow boiling range distillate fractions each of which has a boiling range which is not greater than about 45 C. at mm. of mercury pressure and at least one of which has a boiling point range which is about C. at 15 mm. of mercury pressure and contains as normal parafiin waxes substantially only Cu to Can-normal paraffin hydrocarbons, wherein n is an integer from about 20 to about 35, and as normally solid nonstraight-chain paraiiins substantially only isomers of said normal parafiin hydrocarbons, and the melting point of the Cn-normal parafiin hydrocarbon present is higher than the melting point of the highest melting isomeric hydro- \carbon present; intimately mixing said fraction with a solvent proportion of a polar solvent for said fraction of paraflin hydrocarbons; adjusting the temperature of the resulting mixture to a temperature at which allof the normal paraifin hydrocarbons present and at least a substantial proportion of the iso-paraflinic hydrocarbons present which are normally solid at about C. are separated as a solid phase mixture of waxes; separating the resulting solid wax mixture from the solvent-oil solution; intimately mixing the separated solid wax mixture with a solvent proportion of a polar solvent therefor; adjusting the temperature of the resulting mixture to a temperature below the melting point of the Cn-normal paraflin hydrocarbon present and at which the normal parafilns therein are substantially insoluble but above the temperature at which any appreciable amount of iso-paraffins therein separates as solid material, thereby producing a precipitate of substantially all of the normal paraffin waxes present in said fraction substantially free from isomeric hydrocarbons and a solution in said solvent of the normally solid iso-parafiinic hydrocarbons in said solid wax mixture; and separating the precipitate of normal parailin waxes from the solution of solvent and iso-paraflinic hydrocarbons. v

16. In a process for dewaxing a waxy mineral oil which contains both normal paraflin hydrocarbon waxes and isomers thereof extending over the range of C20 to Gas-hydrocarbons, which isomers have a boiling range at least substantially co-extensive with the boiling range of said normal parafiin hydrocarbon waxes, the improvement which comprises the steps of separating from said waxy mineral oil a number of narrow boiling range distillate fractions each one of a plurality of which has a boiling range of about 20 C. at 15 mm. of mercury pressure and con tains as normal paraflin hydrocarbons substantially only hydrocarbon waxes which differ by only two carbon atoms per molecule and as nonstraight-chain paraffin hydrocarbons only isomers of said normal paraflin hydrocarbons, whereby the melting point of the lowest molecular weight normal parafiin present in each of said plurality of fractions is higher than the melting point of the highest melting isomeric hydrocarbon present in the same fraction; intimately mixing each of said plurality of fractions separately with a solvent proportion of a polar solvent for said fraction of paraffin hydrocarbons; separately adjusting the temperature of each of said resulting mixtures to a temperature 26 at least 15 C. below the melting point of the lowest melting normal paraffin hydrocarbon present therein and at which said lowest melting normal parafiin hydrocarbon is substantially insoluble in the solvent present but above the temperature at which any appreciable amount of isomeric parafiins therein separates as solid material,

thereby producing precipitate of substantially all of the normal paraiiin waxes in the respective fractions and solutions in said solvent of the remaining portions of said fractions; and separating the precipitates of normal paraflin waxes from the respective solvent solutions of isomeric hydrocarbons, each of said separated precipitates of normal paraffin waxes having the properties substantially of a single molecular species.

1'7. In a process for dewaxing a waxy mineral oil which contains both normal parafiln hydrocarbon waxes and isomers thereof extending over the range of C20 to Casi-hydrocarbons, and ammatic hydrocarbons, which isomers have a boiling range at least substantially co-extensive with the boiling range of said normal paraffin hydrocarbon waxes, the improvement which comprises the steps of: separating from said waxy mineral oil a plurality of narrow boiling range distillate fractions at least one of which has a boiling range which is not greater than about 45 C. at 15 mm. of mercury pressure and selected so that it contains the Cze-normal parafiin hydrocarbon, whereby said fraction contains only Cn to 011+;- normal paraffin hydrocarbons, including the Czenormal paraffin, and isomers thereof, and contains no other hydrocarbon waxes, and the melting point of the Cn-normal paraflin present is higher than the melting point of the highest melting isomeric hydrocarbon present; dissolving said fraction of hydrocarbons in approximately an equal part by weight of methyl ethyl ketone; cooling the resulting solution to a temperature of about 5 0., thereby producing a precipitate of substantially all of the C11. to Cn+4-I101'- mal paraiiin hydrocarbons present in said fraction and substantially free from isomeric hydrocarbons and a solution in the methyl ethyl ketone of the remaining portion of said fraction; and separating the precipitate of normal paraffin waxes from the solution of solvent and isomeric hydrocarbons.

18. The process of claim 17, wherein the separated solution of methyl ethyl ketone and isomeric hydrocarbons resulting from the last step is cooled to a temperature of about 10 to -15 0., thereby producing a residual plastic wax mass of normally solid isomeric paraliin waxes and a solvent solution of the remaining portion of said fraction; and separating the residual plastic wax mass from the solvent solution.

AUGUST A. SCHAERER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

2. A PROCESS FOR THE SEPARATION OF STRAIGHTCHAIN PARAFFIN WAXES FROM A PARAFFINIC WAXY MIXTURE OF STRAIGHT-CHAIN PARAFFIN WAXES AND NONSTRAIGHT-CHAIN PARAFFIN WAXES AT LEAST SOME OF WHICH STRAIGHT-CHAIN PARAFFIN WAXES HAVE MELTING POINTS BELOW THE MELTING POINTS OF AT LEAST SOME OF SAID NON-STRAIGHT CHAIN PARAFFIN WAXES PRESENT THEREIN, WHICH PROCESS COMPRISES: SEPARATING FROM SAID WAXY MIXTURE BY DISTILLATION A PLURALITY OF DISTILATE FRACTIONS EACH OF WHICH HAS A BOILING POINT RANGE OF NOT MORE THAN ABOUT 40* C., CONTAINS BOTH STRAIGHT-CHAIN PARAFFIN WAXES AND NON-STRAIGHT-CHAIN PARAFFIN WAXES, AND THE NUMBER OF CARBON ATOMS PER MOLECULE OF ALL OF THE PARAFFIN WAXES PRESENT THEREIN DIFFERS BY NO MORE THAN FOUR CARBON ATOMS, WHEREBY THE MELTING POINT OF THE LOWEST MELTING STRAIGHTCHAIN PARAFFIN WAX PRESENT IN A GIVEN ONE OF SAID FRACTIONS IS HIGHER THAN THE MELTING POINT OF THE HIGHEST MELTING NON-STRAIGHT CHAIN PARAFFIN WAX 